Animals are marked for identification in a variety of applications by a variety of methods. The ability to accurately identify and track individual animals is obligatory in research environments where animals are exposed to different experimental conditions, in the management of colonies of genetically modified animals for which multiple genotypes are present, and in breeding stocks where it is useful to track which animals possess certain desirable and undesirable traits.
To date, methods for identification have largely been dominated by ear punching, ear notching, ear tagging, toe clipping, and manual tail tattooing. The inherent limitations of these methods are becoming increasingly well publicized, and compromise the ability to accurately track animals as colonies become larger and more complex.